#include <iostream>
#include <vector>

using namespace std;

class Solution
{
public:
    void duplicateZeros(vector<int>& arr)
    {
        int cur = 0, dest = -1;
        int n = arr.size();
        while (cur < n)
        {
            if (arr[cur])
                dest++;
            else
            {
                dest += 2;
            }
            if (dest >= n - 1)
                break;
            cur++;
        }
        if (dest == n)
        {
            arr[n - 1] = 0;
            cur--, dest -= 2;
        }
        while (cur >= 0)
        {
            if (arr[cur])
            {
                arr[dest--] = arr[cur--];
            }
            else
            {
                arr[dest--] = 0;
                arr[dest--] = 0;
                cur--;
            }
        }

    }
};

int main()
{
    vector<int> arr{ 1,0,2,3,0,4,5,0 };
    Solution xz;
    xz.duplicateZeros(arr);

    for (auto e : arr)
    {
        cout << e << " ";
    }

	return 0;
}